Soil Water Content Changes with Cover Crops between No-till Wheat and Grain Sorghum.

The addition of double crops and cover crops into no-till systems has become popular in recent years as a means of increasing cropping system intensity and diversity. A primary concern of producers in areas where water often limits yield is the possibility that these fallow replacements may reduce the amount of soil water available for the next grain crop, potentially reducing yields. The objective of this study was to evaluate the effect of cover crops and double-crop soybean on soil-profile water content and sorghum yield in a winter wheat-grain sorghum-soybean, no-till cropping system. Treatments were chemical fallow, double-cropped soybean, and four types of cover crops planted after wheat harvest. Data were collected in 2014 to 2016 from a long-term experiment established in 2007 near Manhattan, KS. Summer cover crops were terminated with a roller/crimper in September. Cool-season cover crops were terminated by freezing temperatures over winter. Volumetric soil water content was measured to a depth of 1.37 m in 2014 and 2.74 m in 2015 using a neutron probe. Double-cropped soybean and all cover crops reduced soil water content compared to chemical fallow, but tillage radish reduced soil water content to the greatest depth and to the greatest extent. Before sorghum planting in the spring of 2015, soil water content had recharged so that it was similar for all treatments. Before sorghum planting in the spring of 2016, profile soil water content in plots with sorghum sudangrass and forage soybean did not significantly differ from chemical fallow, but was reduced with double-crop soybean, crimson clover, and tillage radish. In both years, yields of the following sorghum crop were reduced only in plots with the sorghum-sudan cover crop, indicating that residue amount and quality likely had a greater influence on sorghum yield than soil water content at sorghum planting.